Smile for the Camera

This is "Tough Guy", and I think he's a big brown bat, Eptesicus fuscus, based on what I can see of his dentition, the shape of his tragus, and from what I've gathered from the other bats I've caught in the building. I forget what number Tough Guy is this season, I lose track of these things. But anyway, he's a male as far as I can tell, which is rare compared to females. For those that don't know, I do bat rescue in the dormitories here. He's really quite nice, but likes to put on his tough guy display now and then, hence his name. It's not so much a display of ferocity as it is a desperate act of a tiny creature to scare off the much larger and potentially dangerous human; me.

This is another photo of the same bat, "Tough Guy":

My ID is based on the collective information I've gathered from all the photos of bats I've caught in the building, however, the possibility may exist that there is more than one species of bat roosting in the building. Another possible candidate is the evening bat, Nycticeius humeralis, and the little brown myotis, Myotis lucifugus. Here are photos of other bats I've caught in the same building:

Along with the above photos, I've been using the following links to attempt a positive identification of all the bats I've caught in the building, as well as the corresponding Google, Wikipedia, and EOL.org pages to each species I look into: